Lecture 11

Question 1

What leads to internal DNA damage?

Answer 1

Oxygen free radicals

Question 2

What causes ATM and ATR to be activated?

Answer 2

DNA damage

Question 3

What do ATM and ATR Activate?

Answer 3

CHK2 and CHK1

Question 4

What does wee1 do?

Answer 4

Inhibitory kinase, inhibits CDKs

Question 5

What is CDC25?

Answer 5

Activating phosphatase, removes inhibitory phosphate from CDK

Question 6

What does ATM react to?

Answer 6

DNA double stranded breaks

Question 7

What does ATR react to?

Answer 7

Stalled DNA replication forks

Question 8

How does ATM lead to G1 arrest?

Answer 8

ATM phosphorylates CHK2, inhibiting it, inhibiting cyclin A/E, cell can’t enter S phase. Also activates phosphorylates/p53 which activates p21 which inhibits CDKs, so cell stops at G1.

Question 9

What’s CDC25’s role in G1 arrest after DNA damage?

Answer 9

Is phosphorylated by CHK1 so can’t remove phosphorylation on CDK, so rapidly arrests G1

Question 10

What does cyclin D sense?

Answer 10

Growth signals